Effects of implementation of co-generation in the district heating system of the Faculty of Mechanical Engineering in Nis

Abstract

Implementation of co-generation of thermal and electrical energy in district heating systems often results with higher overall energy efficiency of the systems, primary energy savings and environmental benefits. Financial results depend on number of parameters, some of which are very difficult to predict. After introduction of feed-in tariffs for generation of electrical energy in Serbia, better conditions for implementation of co-generation are created, although in district heating systems barriers are still present. In this paper, possibilities and effects of implementation of natural gas fired cogeneration engines are examined and presented for the boiler house that is a part of the district heating system owned and operated by the Faculty of Mechanical Engineering in Nis. At the moment, in this boiler house only thermal energy is produced. The boilers are natural gas fired and often operate in low part load regimes. The plant is working only during the heating season. For estimation of effects of implementation of co-generation, referent values are taken from literature or are based on the results of measurements performed on site. Results are presented in the form of primary energy savings and greenhouse gasses emission reduction potentials. Financial aspects are also considered and triangle of costs is shown.

Planning of installations in prefabricated buildings

“…U montažnim objektima uvek se primenjuje dvocevni sistem centralnog toplovodnog grejanja pri čemu topla i hladna voda nikad ne prolaze kroz iste cevi. "Kroz otvor sa gornje strane u radijator se uvodi topla voda, a ohlađena nakon što je radijatoru predala određenu količinu toplote, odlazi kroz donji otvor" [12].…”

Smart municipal energy grid within electricity market

“…Natural gas price of 0.3-0.4 €/Nm3 for the small consumer and 0.2-0.1 €/Nm3 at connection to the gas transport network for Republic of Serbia have been assumed. Internal rate of return (IRR) of 6.92, with payback period is almost 11 years discount rate (8%) has been found in study for the CHP plant in Republic of Serbia [14]. In another study [12] also for Republic of Serbia payback period of 9.8-11 years for electricity only with feed in tariff, and 4.6 years for electricity and heat sold, but with 15-20% interest ratio, has been calculated.…”

“…For heat production only it is hard to run units for more than 2,500-3,000 hours per year [14] therefore utilization should be increased selling the energy to the national grid within feed in tariff scheme [12,15,16] or participating at electricity markets. The specific investment costs for the CHP plant based on biogas engine vary with the plant size 800-9,000 €/kW el [17][18][19].…”

“…Most of the economic studies are based on simplification of an assumed utilization ratio of the biogas, natural gas plants and a feed in contract to sell at agreed electricity price [14,22]. Utilization ratio is a bit less due to load management in smart municipal grid [24].…”

Sustainable urban development and industrial pollution

“…Besides that, introduction and application of state-of-the-art methods of pollution control in thermal power plants has significantly facilitated and speeded up the control system and has had a positive impact on the quality of living environment as a whole (Mikulandrić et al, 2012). The research undertaken in the field of application of cogeneration plants will also result in an improved situation in this field, as cogeneration plants have numerous economic and environmental advantages (Stojiljković et al, 2010), but there are numerous barriers for faster economic and technological development (Filipović and Miljković, 2014;Filipović and Miljković, 2011).…”